Issue Archive

Replacing the mechanical check-valve
in a Stirling engine with a micromachined,
non-moving-part flow diode
eliminates moving parts and reduces the
risk of microparticle clogging.

At very small scales, helium gas has sufficient
mass momentum that it can act as a
flow controller in a similar way as a transistor
can redirect electrical signals with a smaller
bias signal. The innovation here forces helium
gas to flow in predominantly one direction
by offering a clear, straight-path
microchannel in one direction of flow, but
then through a sophisticated geometry, the
reversed flow is forced through a tortuous
path. This redirection is achieved by using
microfluid channel flow to force the much
larger main flow into this tortuous path.

While microdiodes have been developed
in the past, this innovation cascades
Tesla diodes to create a much
higher pressure in the gas bearing supply
plenum. In addition, the special
shape of the leaves captures loose particles
that would otherwise clog the
microchannel of the gas bearing pads.

Question of the Week

This week's Question: A recent study created by the Arizona-based Paragon Space Development Corporation says its life support system could help humans survive on Mars. The proposed Environmental Control and Life Support System, the company says,...